Given:
from the name of a reference frame in which a position is known.
[1,m] = size(from); char = class(from)
to the name of a reference frame in which it is desired to represent
the position.
[1,l] = size(to); char = class(to)
et epoch in ephemeris seconds past the epoch of J2000 (TDB) at which
the position transformation matrix should be evaluated.
[1,n] = size(et); double = class(et)
the call:
rotate = cspice_pxform( from, to, et )
returns:
rotate operator(s) that transform position vector(s) from the
reference frame 'from' to frame 'to' at epoch 'et'
If [1,1] = size(et) then [3,3] = size(rotate)
If [1,n] = size(et) then [3,3,n] = size(rotate)
double = class(rotate)
'rotate' returns with the same vectorization measure (N)
as 'et'.